Vetting a maintainer is non-zero work. But it's also not all that much. Especially if said maintainer has already contributed meaningful PRs against your repository.
While you're technically correct that people don't owe anyone anything, I've often had the experience of using an open source library that was otherwise excellent, except that it had critical bugs that hadn't been patched, or that it hadn't been updated to work with the latest versions of it's dependencies. Popular repositories like this often have tens of high-quality pull-requests fixing these issues, but using them is non-trivial because you'd have to merge everything. These PRs pile up for a few months until someone realises that the repo is unmaintained and forks. At which point you have two versions of the project (often with the same name), and everyone is left to figure out which one they should use.
It would save everyone a lot of bother if maintainers of these repositories took half an hour to update everyone that they didn't have time to maintain the repository and pass the baton on to someone / some people who do.
Sure it would save everyone a lot of bother, but consider the alternate universe where you didn't release your code at all. There's no original repo, no idling PRs, no forks, no "community".
Instead of having to figure out how an existing piece of code works, update deps and merge a couple of PRs myself, I instead have to recreate the entire functionality from scratch.
In our original world, where you did release the code, I still have the option of creating my own library (with the benefit of seeing your implementation!). So by releasing your code, you've given me strictly more options, and therefore made me better off, or at least no worse off.
While you're technically correct that people don't owe anyone anything, I've often had the experience of using an open source library that was otherwise excellent, except that it had critical bugs that hadn't been patched, or that it hadn't been updated to work with the latest versions of it's dependencies. Popular repositories like this often have tens of high-quality pull-requests fixing these issues, but using them is non-trivial because you'd have to merge everything. These PRs pile up for a few months until someone realises that the repo is unmaintained and forks. At which point you have two versions of the project (often with the same name), and everyone is left to figure out which one they should use.
It would save everyone a lot of bother if maintainers of these repositories took half an hour to update everyone that they didn't have time to maintain the repository and pass the baton on to someone / some people who do.